San Jose Medical Center Dermatology Department Family Health Center, 3rd Floor Unit K

SKIN PATCH TESTING

This informational sheet was developed to prepare you for skin patch testing. It provides answers to questions patients ask most often. Be sure to discuss any additional questions or concerns you may have with the dermatologist or the dermatology staff before the test is applied. We appreciate your cooperation in helping to make the testing successful.

 WHAT IS THE PURPOSE OF A SKIN PATCH TEST? Patch testing helps discover possible causes for your dermatitis. Small amounts of a number of substances are taped to your back, to find out if you are hypersensitive (allergic) to them. If a skin rash develops where a particular substance was applied to your skin, it may mean you are allergic to that substance. While there are no FDA-approved allergens for extended testing, this technique is well accepted as the gold standard for evaluating allergic contact dermatitis.

 HOW DO I PREPARE FOR THE PATCH TEST? You may bathe or shower before the test, but do not apply any creams/lotions/oils to your upper body area (arms, back, and chest) unless your physician specifically tells you to do so. If you have a lot of hair on your back, it will be shaved before the patch tests are applied.

 WHAT DO I NEED TO BRING FOR MY VISIT? Your physician may do patch testing with some of the topical products you use regularly. Please bring all your over-the-counter and prescription topical products. This includes soaps, hand sanitizers, hair products, makeup, lip products, and etc. In addition, if there is any suspicion of an allergy to clothing (e.g., uniform, underwear) or protective gear (e.g., gloves, elbow pads), please bring them to the visit.

 HOW ARE THE PATCH TESTS APPLIED? A number of substances are applied to aluminum discs that are taped to your back. These patches must be left on your back for 48 hours. Patches are applied on Monday when you come to the clinic for your first appointment.

 HOW LONG WILL THE PROCEDURE TAKE? It may take the nurse 20-30 minutes to prepare the materials. However, it only takes a few minutes to apply the patches to your back (or other determined area). The patches remain on your back for 48 hours. The patches will be removed when you come to the clinic for your Wednesday appointment.

 HOW DO I CARE FOR THE PATCHES? The patches must be left in place until they are either removed in the Dermatology Clinic, or your dermatologist tells you to take them off. In order to prevent false test results you may not shower, wash your back, or expose your back (or other area that may be used for patch testing) to sun or ultraviolet light during the entire testing period. Tub baths should also be avoided as they can pose a problem because the moist environment can cause patches to lift and peel off your skin.

Do not participate in strenuous activities, movements, or situations that make you sweat. Sweating and/or strenuous movement may cause the patches to fall off. If the patches become

Page 1 of 2 loose, fasten them with the additional tape that is provided. The patches need to maintain in contact with your skin for 48 hours.

 HOW WILL THE PATCH TEST FEEL? It is normal to have mild or moderate itching at the test sites. Do not rub or scratch the test sites. If you feel a burning sensation or severe itching at the site, remove just that portion of the tape and wash off the test material. Please report this to your doctor at the clinic visit.

 HOW DOES THE DOCTOR READ THE PATCH TEST? If you are allergic to one or more of the substances tested, a redness or itchy rash, rarely a blister, will appear on the corresponding test area. The substances producing these skin reactions could be the cause of your skin problem. Your doctor will discuss this with you. Redness and itching usually disappears after a few days.

 HOW DO I REMOVE THE PATCHES AT HOME IF MY DOCTOR ASKS ME TO? Remove the tape from your back by pulling each one off from the top. Place the tape on wax or plastic paper. Put the patches in a bag to bring with you to your next clinic visit. Retrace the markings on your back with a ballpoint pen to be sure that they are easy to see. Do not wash your back or sunbathe for several days unless your physician tells you to do so.

 WHAT ELSE DO I NEED TO KNOW? Your physician may recommend a delayed reading. Sometimes a reaction does not appear before the third or fourth day. A delayed reading will allow these reactions to be detected. Also, patch test chemicals may irritate the skin and mimic an allergic reaction. Usually irritation fades within two days after the test is removed; allergic reactions stay the same or increase in intensity.

If your doctor does not recommend a delayed reading, but you notice a new red spot develop at the test site, please return to the Dermatology Clinic. If this is not possible, call your doctor and note the exact location of the spot. You may develop an allergy from the testing itself. The risk is very low but something that you should know about.

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